3. Sen. Mitch McConnell, R-Ky.

Alex Wong / Getty Images

The enforcer of Republican Party discipline, Senate Minority Leader McConnell is among the key architects of his party's stance on environmental issues. In 2009, when Sen. Lindsey Graham of South Carolina was among the few Republicans willing to discuss a bipartisan climate bill with Democrats, it was McConnell who reportedly convinced him to back away. This spring he led a failed effort to block the EPA's authority to regulate greenhouse-gas emissions and overrule its finding that climate change threatens public health -- tantamount to a statement that politicians know more about the dangers of climate change than scientists.

The enforcer of Republican Party discipline, Senate Minority Leader McConnell is among the key architects of his party's stance on environmental issues. In 2009, when Sen. Lindsey Graham of South Carolina was among the few Republicans willing to discuss a bipartisan climate bill with Democrats, it was McConnell who reportedly convinced him to back away. This spring he led a failed effort to block the EPA's authority to regulate greenhouse-gas emissions and overrule its finding that climate change threatens public health -- tantamount to a statement that politicians know more about the dangers of climate change than scientists. (Alex Wong / Getty Images)

The enforcer of Republican Party discipline, Senate Minority Leader McConnell is among the key architects of his party's stance on environmental issues. In 2009, when Sen. Lindsey Graham of South Carolina was among the few Republicans willing to discuss a bipartisan climate bill with Democrats, it was McConnell who reportedly convinced him to back away. This spring he led a failed effort to block the EPA's authority to regulate greenhouse-gas emissions and overrule its finding that climate change threatens public health -- tantamount to a statement that politicians know more about the dangers of climate change than scientists.